Inside every sane person there’s a madman struggling to get out. No one goes mad quicker than a totally sane person.
Insanity is relative. It depends on who has who locked in what cage.
Insanity is contagious.
Insanity is catching.
Insanity depended on your point of view and if it was the view through your own underpants then everything looked fine.
Bunch together a group of people deliberately chosen for strong religious feelings, and you have a practical guarantee of dark morbidities expressed in crime, perversion, and insanity.
A madman in particular has always a very strong reason for the crimes he commits.